This invention relates to a golf club shaft formed of a carbon fiber-reinforced plastic (CFRP) and to a golf club using same.
Japanese patent publication (Tokkyo Kokoku) No. 60-39388 discloses a CFRP golf club shaft which is composed of an inner layer formed of a first, carbon fiber-reinforced plastic and containing a first carbon fiber group oriented at an angle in the range of 25 to 65 degrees with respect to the longitudinal axis of the shaft, and an outer tubular layer provided around said inner layer and formed of a second, carbon fiber-reinforced plastic and containing a second carbon fiber group oriented at an angle in the range of 0 to 15 degrees with respect to the longitudinal axis of the shaft.
While such a known club shaft is lighter in weight and provide an improved golf club which can hit a golf ball longer distance as compared with conventional steel club shafts, the flexural rigidity thereof is still insufficient to satisfy the demand of hard hitter players who can swing their clubs with a high club head speed. More specifically, when the known CFRP club is swung, the shaft bends excessively along it longitudinal axis during the top swing and down swing so that the movement of the club head is excessively retarded. Therefore, the player cannot shot the ball with intended swing. Though stiffness can be imparted to the shaft by increasing the thickness of the wall thereof, this causes increase in weight of the shaft.